Normal Sudoku rules apply.
The digit 6 can't be within a chess knight's move of digits 6, 7, 8 and 9.
Solution code: Column 8, 9
on 8. March 2021, 20:38 by akodi
Nice :)
The Knight in Chess is called Springer in German, btw
on 8. March 2021, 05:32 by panthchesh
Thanks for the puzzle! :) (and thanks for pausing between publishings! )
on 7. March 2021, 16:45 by Ryx
I recently reworked one of my earlier (unsolved) puzzles that has a 6789 theme as well ;-) I've been waiting to publish it, but just published another one and don't want to flood with new puzzles ...